This invention relates to oil-soluble phenolic polymers. More particularly it relates to oil-soluble phenolic condensation polymers useful as antioxidants.
Antioxidants are of great use in the food industry today. They make acceptable shelf lives possible for a wide range of products especially products containing fats and oils by delaying the onset of rancidity or spoilage. They also make possible the substantial retention of nutritional and flavor values in edibles. Notwithstanding these benefits, safety questions are causing people in many lands to reevaluate and often restrict or eliminate the use of antioxidants in edibles. One approach to lessening or eliminating the risks of toxicity of food additives was set forth by Zaffaroni in U.S. Pat. No. 3,876,816 issued Apr. 18, 1975. There it is taught that by forming a food additive (in that case a sweetener) into a nondegradable macromolecule, one can prevent absorption of the additive through the gastrointestinal tract wall into the body when the additive is eaten. This principle can be applied to antioxidants with generally good results. However, the obtaining of a nonabsorbable polymeric antioxidant suitable for easy commercial use in edible oils is difficult. A major problem lies in solubility. As a rule, polymer solubility in oil is inversely proportional to the polymer's molecular size. Hence, as one macromolecularizes an antioxidant, one encounters decreasing solubility, often to unacceptably low levels. Another problem is stability. For unknown reasons, many antioxidant species, when made into polymers, undergo major drops in stability. A third problem with macromolecularization of antioxidants is a difficulty with regularly achieving a proper molecular weight. It is required for substantial nonabsorption to minimize the amount of polymer having a molecular weight below about 1000 daltons, especially below about 500 daltons. Similarly, for solubility and functionality reasons, it is desirable to minimize the amount of very large molecules -- say having a molecular weight above about 40,000 daltons.
The present invention provides a limited group of polymeric antioxidants which minimize these problems of prior materials. They have good antioxidant activity, good solubility in oils, good stability and proper molecular weights.